Texas is home to a tremendous variety of native fauna, a consequence of its immense size and unique geographical location. The state functions as a biological crossroads where four major North American climate zones converge, including the arid western deserts, the humid eastern forests, the northern Great Plains, and the subtropical Gulf Coast. This convergence creates a massive range of habitats, supporting a rich diversity of animal life that has naturally evolved within the state’s boundaries.
How Texas Ecoregions Shape Fauna
Texas is divided into ten distinct ecological regions, or ecoregions, defined by consistent patterns of geology, climate, soil, and vegetation. These large geographic areas are defined by consistent patterns of geology, climate, soil, and vegetation. The immense difference in precipitation, ranging from only eight inches annually in the far west to 56 inches in the east, is a primary driver of this ecological separation.
The Piney Woods of East Texas, for example, are characterized by high rainfall, acidic sandy loams, and dense forests dominated by Loblolly and Shortleaf pines. This moist, heavily wooded habitat supports species accustomed to eastern deciduous forests.
Moving west, the Edwards Plateau, known as the Texas Hill Country, features rugged limestone terrain, deep canyons, and extensive cave systems. The vegetation here is primarily oak and juniper woodlands adapted to stony hills and intermittent springs. The Gulf Prairies and Marshes form a narrow coastal band defined by high humidity, warm temperatures, and a long growing season. This region now includes salt marshes and barrier islands. In stark contrast, the Trans-Pecos region of West Texas is an arid landscape of desert valleys, plateaus, and mountain ranges, supporting drought-tolerant vegetation such as creosote bush and various cacti.
Iconic and Widely Distributed Mammals
Texas is home to approximately 148 native terrestrial mammal species. The Nine-banded Armadillo (Dasypus novemcinctus), designated the state small mammal, is a widespread species recognized by its bony, protective carapace. This insectivore is highly adaptive, inhabiting diverse environments from eastern forests to western scrub deserts.
The White-tailed Deer is the most common large native mammal, flourishing in nearly all of Texas’s ecoregions, from the thickets of the South Texas Plains to the woodlands of the Hill Country. Another highly visible native is the Mexican Free-tailed Bat (Tadarida brasiliensis), the state flying mammal. This species is famous for forming the largest known bat colony in the world at Bracken Cave near San Antonio, where millions of individuals roost.
Widespread native carnivores include the highly adaptable Coyote, found in all ecoregions, and the Mountain Lion (Cougar), a large predator found mostly in the remote western and southern parts of the state.
Diverse Native Reptiles and Amphibians
The state’s variety of environments results in a particularly rich herpetofauna, hosting 71 species of amphibians and 160 species of reptiles. Reptiles, with their scaly skin and ability to regulate body temperature, are well-suited to the arid and semi-arid conditions prevalent across much of Texas.
A symbolic reptile is the Texas Horned Lizard (Phrynosoma cornutum), a flat-bodied lizard with distinct cranial spines. This species specializes in consuming harvester ants and is most common in the western and southern parts of the state. Among the native snakes, the Western Diamondback Rattlesnake is a widespread and common venomous species, found across the western two-thirds of Texas.
A nonvenomous example is the Texas Rat Snake, a large, powerful constrictor often found in wooded areas, known for its ability to climb trees and prey on birds and rodents. Amphibians, such as the Texas Toad (Anaxyrus speciosus), are largely dependent on water due to their permeable skin. This toad is adapted to the dry climate by spending long periods underground, emerging only after heavy rains to quickly breed in temporary pools.
Species Found Only in Texas (Endemics)
Endemic species are organisms whose entire native range is restricted to the state’s borders. These species are particularly sensitive to localized changes. Their existence is often linked to highly specific, isolated habitats like subterranean cave systems or particular river stretches.
These species highlight how geological isolation and specialized microclimates have fostered unique evolutionary paths within Texas:
- The Austin Blind Salamander (Eurycea waterlooensis), a small amphibian found only in the underground waters of the Barton Springs segment of the Edwards Aquifer. It is completely sightless and possesses external gills.
- Cagle’s Map Turtle (Graptemys caglei), a freshwater turtle found only in the Guadalupe, San Antonio, and San Marcos Rivers.
- The Devil’s River Minnow (Dionda diaboli), a small fish endemic to a few spring-fed tributaries in the Pecos and Devil’s River drainages of the Trans-Pecos region.
- The Guadalupe Bass (Micropterus treculii), designated the state fish, is also endemic to the streams of the Edwards Plateau.